In the entire U.S. hospital healthcare system, four of the top ten most expensive conditions requiring hospitalization are related to the care of infants. One of these four is "lack of oxygen in utero" (birth asphyxia), which requires an average stay of almost 13 days at a cost of nearly $40,000. Fetal heart rate monitoring is intended to detect signs of fetal distress due to oxygen starvation of the fetus. Unfortunately these methods of fetal monitoring are subject to a high incidence of false positives, resulting in more than 200,000 unnecessary cesarean section deliveries in the U.S. each year with an associated cost of over $1 billion per year. Clinicians have long recognized that direct measurement of fetal oxygen status would provide a more definitive indication of fetal well-being. This requires the use of pulse oximetry, the continuous, noninvasive measurement of oxygen saturation in arterial blood. Intrapartum fetal pulse oximetry has only recently been made available as a commercial product, but with severely limited success. Kestrel Labs, Inc. is developing a fetal pulse oximetry sensor for continuous measurement of fetal oxygen status and heart rate from a single, easily accessible monitoring site located on the fetal scalp. Unlike current sensor technology, which uses a "blind" insertion method, has no means for securing the sensor to the fetus, and requires repositioning nearly 4 times an hour, the Kestrel Labs fetal oximetry sensor will be easy to insert, securely attach to the fetal scalp, and will require no maintenance once placed. This SBIR Phase II effort focuses on the development and calibration of a pre-production, biocompatible version of the sensor that has an integral "deployment" apparatus for transvaginal insertion onto the fetal scalp.